If RIM makes BlackBerry APIs available on a QNX kernel, developers won't have much trouble adapting.

OTOH, if they ported the API's to Linux, they might still have developers come 2013.

It seems like a decision made to rationalize spending that money on QNX (possibly spiced with a desire to retain "proprietary" secret sauce factor in the overall system). Nothing wrong with that, especially if you work in HR instead of engineering.

The kernel they run is about as relevant to a developer as the color of the case.

I'm not talking just about the kernel (neither QNX or Linux are just about the kernel). You could layer BB API's over a full Linux system. I've said it before, but RIM should have implemented the full proprietary BB stack over the MeeGo core.